Stress Engineering of Solid State Electrolytes to Improve Electrochemical Performance

All-solid-state lithium metal batteries have the potential to outperform liquid-based lithium-ion batteries in capacity, energy density, and safety; however, the practical implementation of solid-state electrolytes (SEs) faces serious challenges, in large part because lithium dendrites readily penetrate through SEs, leading to short circuits and cell failure. In this work, we present a new paradigm for mitigating dendrite induced short circuiting: surface stress engineering using ion implantation in SEs. Unlike existing methodologies involving high stack pressures or buffer layers, our approach to mitigating dendrite penetration focuses on inducing residual compressive stress at the surface of SEs through innovative surface modification. This ion implantation method affords control over the depth and concentration of implanted ions[YW1] , with the flexibility to select from a wide range of implantation conditions. We have demonstrated this concept using fluorine ion implantation into Li₇La₃Zr₂O₁₂ (LLZO), a garnet-type SE, as a model material. This presentation will cover the use of ion implantation to engineer mechanical and chemical properties at the surface and subsurface of SEs. It will also address the impact ion implantation has on the electrochemical properties of the implanted material. We characterized the implanted SE samples using Synchrotron X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), and X-ray Photoelectron Spectroscopy (XPS). We also studied the electrochemical performance of the ion implanted SEs against lithium metal using Electrochemical Impedance Spectroscopy (EIS) and galvanostatic cycling. This presentation will examine evidence from these characterizations to highlight how ion implantation enables improved electrochemical performance and enhanced air stability in LLZO, and it will provide new insights into a scalable dendrite suppression strategy for designing solid-state batteries.